Substrate processing system and substrate processing method

ABSTRACT

A coating unit for coating a substrate with a treatment solution and a peripheral aligner, which has a mounting table rotatable and movable in at least one direction and irradiates the peripheral portion of the substrate on the mounting table with light from an irradiating portion to expose a coating film on the substrate, are provided in a substrate processing system. The peripheral aligner has film thickness measuring means provided with a sensor member for measuring a film thickness of the coating film. It is not necessary to separately provide a unit for measuring the film thickness outside of the system, thus preventing the substrate from being contaminated or dropped to be damaged when the film thickness is measured.

This application is a divisional of U.S. patent application Ser. No.09/694,820 filed Oct. 24, 2000 now U.S. Pat. No. 6,431,769 issued Aug.13, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing system and asubstrate processing method.

2. Description of the Related Art

In the photography in processes of semiconductor device fabrication, forexample, resist coating treatment for forming a resist film on thesurface of a semiconductor wafer (described as “a wafer” hereinafter),exposing processing for exposing the wafer by irradiating a patternthereon, developing treatment for developing the exposed wafer, and thelike are performed. Processing units for performing such processing andtreatments are integrated into one system to form a coating anddeveloping system.

Incidentally, it is important for the resist film, which is coated onthe wafer before the exposing processing of a pattern, to have apredetermined film thickness in order to suitably perform predeterminedlithography. Therefore, the film thickness of the resist film on thewafer is inspected before the pattern is exposed, and when it is over apredetermined allowable value, the rotational frequency of the wafer ina coating unit, for example, is controlled based on the inspection.

Conventionally, an operator selects a wafer before exposing processingout of the coating and developing system to perform the inspection ofthe film thickness of the resist film with use of a film thicknessmeasuring unit for inspection provided separately from the coating anddeveloping system.

SUMMARY OF THE INVENTION

However, it is necessary to transfer the wafer from the coating anddeveloping system to the unit for inspecting the film thickness in sucha manner, thus requiring both labor and time. Further, there is a dangerthat the wafer is contaminated while being transferred. Furthermore,there is a risk that an operator drops the wafer by mistake.

The present invention is made in view of the aforesaid points and itsobject is to inspect the film thickness of the resist film on the waferin the single system by providing film thickness measuring means in aperipheral aligner in which the existing mechanism in the coating anddeveloping system can be utilized.

A first aspect of the present invention is a processing system forprocessing a substrate, comprising a coating unit for coating thesubstrate with a treatment solution and a peripheral aligner having amounting table rotatable and movable in at least one direction andirradiating the peripheral portion of the substrate on the mountingtable with light from an irradiating portion to expose a coating film onthe substrate, the peripheral aligner having film thickness measuringmeans provided with a sensor member for measuring the film thickness ofthe coating film.

A second aspect of the present invention is a method of processing asubstrate with use of a substrate processing system, the substrateprocessing system comprising a peripheral aligner for irradiating theperipheral portion of the substrate with light to expose a coating filmapplied on the substrate and a unit for measuring a film thickness ofthe coating film, the method comprising the step of irradiating theperipheral portion of the substrate with the light to expose the coatingfilm after measuring the film thickness of the coating film on thesubstrate. In this case, the step of measuring the film thickness of thecoating film once again may be added after the coating film is exposed.

A third aspect of the present invention is a process of performingprocessing on a substrate with use of a substrate processing systemcomprising a peripheral aligner, a unit for measuring a film thicknessof a coating film, and further a coating unit for coating the substratewith the coating film, the process comprising the steps of using a testsubstrate as the substrate of which film thickness is measured,performing predetermined coating treatment on a production substrate inthe coating unit when a measurement value is within an allowable rangeas a result of a measurement of the film thickness, and measuring thefilm thickness of another test substrate subjected to coating treatmentin the coating unit after making a necessary correction to the coatingunit when the measurement value is out of the allowable range.

According to the present invention, the peripheral aligner has amounting table rotatable and movable in at least one direction.Therefore, it is possible to suitably perform a film thicknessmeasurement at, for example, a predetermined point on the substrate byutilizing such mechanism, and in addition it is not necessary to providea unit having the film thickness measuring means separately from thesubstrate processing system.

In the substrate processing method according to the present invention,the film thickness measurement and peripheral exposure are performedusing the same substrate processing system, whereby it is not necessaryto perform the film thickness measurement in another unit which isseparately provided. Moreover, since the coating film on the peripheralportion of the substrate is exposed after the film thickness of thecoating film on the substrate is measured, it is possible to measure thefilm thickness of the coating film before peripheral exposingprocessing, which can be material for determining whether precedingtreatment is properly performed or not.

In the substrate processing method according to the present invention, asubstrate exclusive to test is housed in a cassette beforehandseparately from, for example, a production substrate, more specifically,a substrate which undergoes predetermined processing to be shipped as aproduct, and the film thickness is initially measured with the testsubstrate before coating treatment or subsequent processing is performedon the production substrate. Then, predetermined coating treatment issubsequently performed on the production substrate in the coating unitwhen the measurement value is within the allowable range. On the otherhand, when the measurement value is out of the allowable range, anothertest substrate is taken out of the cassette, then subjected to coatingtreatment in the coating unit and the film thickness thereof is measuredafter a necessary correction is made to the coating unit. As a result ofthe measurement, when the film thickness is within the allowable range,processing is performed on the production substrate, and when the filmthickness is out of the allowable range, the correction is again made tothe coating unit and thereafter other test substrates are subsequentlymeasured the film thickness thereof. As a consequence, the yield of theproduction wafer can be improved. The above-described film thicknessmeasurement with the test substrate may be periodically performed in abreak of a lot of the production substrates, or after processing isperformed on a predetermined number of the production substrates.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the invention and the concomitantadvantages will be better understood and appreciated by persons skilledin the field to which the invention pertains in view of the followingdescription given in conjunction with the accompanying drawings whichillustrate preferred embodiments.

FIG. 1 is a plane view showing an appearance of a coating and developingsystem according to the present embodiment;

FIG. 2 is a front view of the coating and developing system in FIG. 1;

FIG. 3 is a rear view of the coating and developing system in FIG. 1;

FIG. 4 is a perspective view of the inside of a peripheral aligner inthe coating and developing system according to the present embodiment;

FIG. 5 is an explanatory view of a vertical section showing a structureof the peripheral aligner in the coating and developing system accordingto the present embodiment;

FIG. 6 is an explanatory view of a transverse section showing thestructure of the peripheral aligner in FIG. 5;

FIG. 7 is an explanatory view showing routes of film thicknessmeasurements on a wafer in time series, which are performed in aperipheral aligner according to a first embodiment;

FIG. 8 is an explanatory view showing routes of film thicknessmeasurements on a wafer in time series, which are performed in aperipheral aligner according to a second embodiment;

FIG. 9 is an explanatory view showing routes of film thicknessmeasurements on a wafer in time series, which are performed in aperipheral aligner according to a third embodiment;

FIG. 10 is an explanatory view in a case where a cover for a filmthickness sensor is attached to the film thickness sensor in theperipheral aligner according to the present embodiment; and

FIG. 11 is a perspective view showing a state where a reflecting objectis provided on a mounting table.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described belowwith reference to the accompanying drawings.

FIG. 1 is a plane view of a coating and developing system 1 as asubstrate processing system according to the present embodiment, FIG. 2is a front view of the coating and developing system 1, and FIG. 3 is arear view of the coating and developing system 1.

As shown in FIG. 1, the coating and developing system 1 has a structurein which a cassette station 2 for carrying, for example, 25 wafersfrom/to the outside to/from the coating and developing system 1 in theunit of cassette and for carrying the wafers W into/from a cassette C, aprocessing station 3 in which various kinds of multi-tiered processingunits for performing predetermined processings one by one in the coatingand developing process are disposed, and an interface section 4 forreceiving and delivering the wafer W from/to an aligner 52 providedadjacent to the processing station 3, are integrally connected.

In the cassette station 2, a plurality of cassettes C are well mountedat predetermined positions on a cassette mounting table 5 serving as amounting portion in a line in an X-direction (a vertical direction onFIG. 1). Further, a wafer carrier 7, which is transferable in thedirection of alignment of the cassettes (the X-direction) and in thedirection of alignment of the wafers W housed in the cassette C (aZ-direction; a vertical direction), is provided to be movable along acarrier guide 8 and is selectively accessible to the respectivecassettes C.

The wafer carrier 7 is structured so as to access also an alignment unit32 and an extension unit 33 which are included in a third processingunit group G3 on the side of the processing station 3 as will bedescribed later.

In the processing station 3, a main carrier unit 13 is provided in thecenter part thereof, and various kinds of processing units aremulti-tiered on the periphery of the main carrier unit 13 to composeprocessing unit groups. In the coating and developing system 1, thereare four processing unit groups G1, G2, G3 and G4, and the first and thesecond processing unit groups G1, G2 are disposed on the front side ofthe coating and developing system 1, the third processing unit group G3is disposed adjacent to the cassette station 2, and the fourthprocessing unit group G4 is disposed adjacent to the interface section4. Further, as an option, a fifth processing unit group G5 depicted bybroken lines can be additionally arranged on the rear side of thecoating and developing system 1.

In the first processing unit group G1, as shown in FIG. 2, two kinds ofspinner-type processing units, for example, a resist coating unit 15 inwhich the wafer W undergoes resist coating, and a developing unit 16 inwhich the wafer W undergoes treatment with a developing solutionsupplied are two-tiered in the order from the bottom. Also in the caseof the second processing unit group G2, a resist coating unit 17 and adeveloping unit 18 are similarly two-tiered in the order from thebottom.

In the third processing unit group G3, as shown in FIG. 3, a coolingunit 30 for cooling the wafer W, an adhesion unit 31 for increasing thefixability between a resist solution and the wafer W, the alignment unit32 for aligning the wafer W, the extension unit 33 for keeping the waferW waiting, prebaking units 34, 35 for performing heat treatment beforeexposing processing, and postbaking units 36, 37 for performing heattreatment after developing and so on are, for example, eight-tiered inthe order from the bottom.

In the fourth processing unit group G4, a cooling unit 40, an extensionand cooling unit 41 for spontaneously cooling the housed wafer W, anextension unit 42, a cooling unit 43, post-exposure baking units 44, 45for performing heat treatment on the wafer W after exposing processing,and postbaking units 46, 47 and so on are, for example, eight-tiered inthe order from the bottom.

In the interface section 4, provided is a peripheral aligner 51 forirradiating the peripheral portion of the wafer W with light to expose aresist film formed on the wafer W, and measuring a film thickness of theresist film if necessary as described later. Moreover, a wafer carrier50, which is provided in the center part of the interface section 4, isstructured so as to be accessible to the extension and cooling unit 41,the extension unit 42 which are included in the fourth processing unitgroup G4, the peripheral aligner 51, and the aligner 52 which is shownby broken lines.

Next, a structure of the peripheral aligner 51 having film thicknessmeasuring means will be explained based on FIGS. 4 and 5.

In a casing 60 of the peripheral aligner 51, provided is a mountingtable 61 for sucking and holding the wafer W. The mounting table 61 isrotatable by a drive mechanism 62 in which a motor, for example, or thelike is incorporated. Further, the drive mechanism 62 is movable on arail 63 extending longitudinally (a horizontal direction in FIG. 5),whereby the mounting table 61 is movable longitudinally (the horizontaldirection in FIG. 5). Above the wafer W, provided are a film thicknesssensor 64 serving as a sensor member for sensing the film thickness ofthe resist film as a coating film with laser light, and a irradiatingportion 65 for irradiating light for exposure.

A fan 66 for suction is attached on one side of the casing 60 and anexhaust port 72 is provided on the other side thereof, whereby draft isformed from the fan 66 toward the exhaust port 72 to interchange anatmosphere in the peripheral aligner 51. The film thickness sensor 64 isarranged on the upstream side from the irradiating portion 65 in thedraft. Moreover, the film thickness sensor 64 is hung up with an arm 67,and the arm 67 is rotatably attached about a rotation shaft 67 adisposed on an edge of a wall of the casing 60 as shown in FIG. 6.Therefore, the arm 67 is rotated by a drive mechanism which is not shownso that the film thickness sensor 64 can be moved away from above thewafer W.

Further, the film thickness sensor 64 is connected to a film thicknesssensor control unit 68 provided outside the casing 60, and the filmthickness sensor control unit 68 converts light detected by the filmthickness sensor 64 into data, stores them, and performs a measurementof the film thickness of the resist film based on the data. Furthermore,the irradiating portion 65 is fixedly provided on the casing 60. Theirradiating portion 65 irradiates light on the wafer W from a lightsource portion which is not shown through a light conduit 69, to exposethe resist film on the periphery of the wafer W. In addition, a laserlight source 70 for emitting light to detect a precise position of thewafer and a CCD sensor 71 for detecting the light are provided, havingthe wafer W vertically sandwiched therebetween.

Next, processes of a test wafer W in the peripheral aligner 51 asstructured above will be described together with a sequence of coatingand developing processes.

First, the wafer carrier 7 takes an unprocessed wafer W out of thecassette C to carry it into the alignment unit 32 included in the thirdprocessing unit group G3. Second, the wafer W, of which alignment iscompleted in the alignment unit 32, is transferred through the adhesionunit 31 and the cooling unit 30 to the resist coating unit 15 or 17 bythe main carrier unit 13. There, the top face of the wafer W is coatedwith a resist solution to form the resist film. After that, the wafer Wis sequentially transferred to the prebaking unit 34 or 35 and theextension and cooling unit 41 to undergo predetermined processing.

Then, the wafer W is taken out of the extension and cooling unit 41 bythe wafer carrier 50, and thereafter transferred to the peripheralaligner 51.

At this time, the fan 66 is operated in the peripheral aligner 51 toform the draft from the fan 66 toward the exhaust port 72 so thatimpurities such as organic substances can be exhausted from the insideof the casing 60 even if they are generated. Additionally, the filmthickness sensor 64 is positioned on the upstream side in the draft,thereby preventing contamination by formation of the draft.

The wafer W, which is transferred to the peripheral aligner 51, isplaced and suction-held on the mounting table 61. The wafer W, which isheld on the mounting table 61, has coordinates of a perimetricalposition thereof recognized by the laser light source 70 and the CCDsensor 71 so that it is determined whether the wafer W is placed on apredetermined position or not.

The measurement of the film thickness of the resist film will beexplained hereinafter, using FIGS. 5, 6 and 7. First, the film thicknesssensor 64, which is moved away from above the wafer W as shown by brokenlines in FIG. 6, is moved to above the center of the wafer W by the arm67. Second, laser light is irradiated from the film thickness sensor 64and the light reflected from the resist film is again detected by thefilm thickness sensor 64 while the wafer W is moved in an X axisdirection (a rightward direction in FIG. 5) by the drive mechanism 62.

The data detected by the film thickness sensor 64 are transmitted to thefilm thickness sensor control unit at any time and stored therein. Aftera while, the wafer W comes to a stop and also the film thicknessmeasurement is brought to a stop when the film thickness sensor 64 ispositioned above the peripheral portion of the wafer W. The filmthickness measurement of one radius of the wafer W is performed by theabove-described processes (FIG. 7(a), incidentally, trajectories of themeasurement by the film thickness sensor 64 are indicated by the arrowsand the order of the film thickness measurement is indicated by thecircled figures). Next, the wafer W is rotated 90 degrees in a θdirection (a counterclockwise direction) by the drive mechanism 62 (FIG.7(b)). This time, the wafer W is moved in a negative X axis direction (aleftward direction in FIG. 5), and the film thickness thereof issimilarly measured by the film thickness sensor 64. Then, the wafer W isbrought to a stop again and also the film thickness measurement comesinto a stop when the film thickness sensor 64 is moved to above thecenter of the wafer W (FIG. 7(c)). The above-described measurement isperformed at every 90 degrees, and finally every film thickness ondiameters orthogonal to each other is measured as shown in FIG. 7(d) andthe film thickness measurement is completed when the wafer W is rotatedone turn (FIG. 7(e)).

Next, the wafer W is moved to below the irradiating portion 65 by thedrive mechanism 62 and brought to a stop at a predetermined position. Atthis time, the arm 67, on which the film thickness sensor 64 is hung, isrotated by the drive mechanism which is not shown to move the filmthickness sensor 64 away from above the wafer W. Thereafter, the wafer Wis rotated in accordance with a predetermined recipe, and a resistcoating film on the peripheral portion of the wafer W is exposed in aprescribed width with the laser light from the irradiating portion 65.

The wafer W, of which peripheral exposing processing is completed, hasthe film thickness measurement once again by the above-describedprocesses. At that time, also a portion on the wafer W which undergoesperipheral exposing processing is measured and the data are stored inthe film thickness sensor control unit 68 so that whether the exposedportion is performed at a predetermined position or not is inspected bythe measured film thickness.

The wafer W, which completed the second measurement of the filmthickness thereof, is carried to the outside of the aligner 51 by thewafer carrier 50 and the inspection of the test wafer W is completed.

As has been described, in the coating and developing system 1 accordingto the present embodiment, it is not necessary to take the wafer out ofthe coating and developing system 1 and the inspection can be performedin a sequence of the processes when the film thickness of the resistfilm is inspected since the peripheral aligner 51 is provided with thefilm thickness measuring means. Therefore, needless time and laborrequired to transfer the wafer W can be reduced. Moreover, since theperipheral aligner 51 is originally provided with the mounting table 61which is necessary for the film thickness measurement, rotatable, andmovable in at least one direction, the film thickness measuring meanscan be provided by utilizing the existing mechanism, whereby it ispossible to measure the film thickness at any point on the wafer W andin addition a cost reduction is expected. Further, the film thicknessmeasurement is performed before and after peripheral exposingprocessing, whereby it is possible to determine not only whether theresist film is correctly formed or not, but also whether peripheralexposure is properly performed or not. Furthermore, the film thicknesssensor 64 for measuring the film thickness is provided on the upstreamside in the draft relative to the irradiating portion 65, whereby it ispossible to prevent the film thickness sensor 64 from being contaminatedand its measuring ability from being deteriorated. Additionally, the arm67 of the film thickness sensor 64 is made rotatable and can be movedaway from above the wafer W during peripheral exposure, therebypreventing the film thickness sensor 64 from being contaminated also inthis respect.

Now, another embodiment of the above-described processes of the filmthickness measurement as shown in FIG. 7 will be described. First,according to a second embodiment, a starting position of a filmthickness measurement is made a predetermined peripheral portion of thewafer W, and the film thickness sensor 64 is operated in the same manneras in the first embodiment to be kept waiting above the peripheralportion of the wafer W. Second, the film thickness measurement isperformed by the film thickness sensor 64 fixed above the wafer W whilethe wafer W is moved in the negative X axis direction (the leftwarddirection in FIG. 5) by the drive mechanism 62 as shown in FIG. 8.

Then, the wafer W once comes to a stop and also the film thicknessmeasurement is brought to a stop when the film thickness sensor 64 ispositioned above the center of the wafer W (FIG. 8(a)). Next, the waferW is rotated 180 degrees in the θ direction (the counterclockwisedirection) by the drive mechanism 62 (FIG. 8(b)). This time, the wafer Wis moved in a positive X axis direction (the rightward direction in FIG.5), and the film thickness thereof is similarly measured by the filmthickness sensor 64. Then, the wafer W is brought to a stop again andalso the film thickness measurement comes to a stop when the filmthickness sensor 64 is positioned above the peripheral portion of thewafer W (FIG. 8(c)). The film thickness measurement on one diameter ofthe wafer W is performed by the above-described processes. Further, themeasurement on another diameter is performed in the same manner as inthe above-described processes (FIGS. 8(a) to 8(c)) by rotating the waferW 90 degrees in the θ direction by the drive mechanism 62 (FIGS. 8(d)and 8(e)). As a result, the film thickness on the diameters orthogonalto each other is measured as shown in FIG. 8(e), and the film thicknessmeasurement is completed when the wafer W is finally returned to thestarting position for the film thickness measurement (FIG. 8(f)). Thesame effect as that in the first embodiment can be obtained if the filmthickness is measured by performing the above-described processes.

Furthermore, a third embodiment will be described. First, the filmthickness sensor 64 is moved to above the center of the wafer W and keptwaiting as shown in FIG. 9. There, the film thickness of the center ofthe wafer W is measured by the film thickness sensor 64 (FIG. 9(a)).Second, the wafer W is moved a predetermined distance in the X direction(the rightward direction in FIG. 5) and brought to a stop (FIG. 9(b)).There, the film thickness is measured while the wafer W is rotated inthe θ direction (the counterclockwise direction) by the drive mechanism62, and the film thickness measurement and the rotation is brought to astop when rotated 360 degrees (FIG. 9(c)). Thereafter, the wafer W isagain moved a predetermined distance in the X direction (the rightwarddirection in FIG. 5) and then brought to a stop, so that the filmthicknesses on concentric circumferences are similarly measured byrotating the wafer W (FIG. 9(d)). The film thicknesses areconcentrically measured toward the perimeter of the wafer W by repeatingthe processes as described above, the film thickness measurement iscompleted when the film thickness measurement of the peripheral portionof the wafer W is finished (FIG. 9(e)).

According to the third embodiment, although the film thickness isconcentrically measured from the center toward the perimeter of thewafer W, the film thickness may be measured from the perimeter towardthe center thereof. In addition, the above-described film thicknessmeasurement is performed by irradiating the laser light from the filmthickness sensor 64 and detecting again the light reflected from theresist film by the film thickness sensor 64, which may be performedeither while the wafer W is moved or after it is once stopped whenmeasured. The same effect as that in the first embodiment can beobtained also in this third embodiment.

A cover 75 serving as a protecting member may be attached to the filmthickness sensor 64 as shown in FIG. 10. The cover 75 is structured soas to be opened during the film thickness measurement and closed at allother times. The opening and closing of the cover 75 is carried out by adrive mechanism which is not shown and controlled by the film thicknesssensor control unit 68. Attaching such cover 75 can more surely preventthe film thickness sensor 64 from being contaminated.

Although the film thickness measurement is performed before and afterthe peripheral exposing processing in the above-described embodiment, itmay be performed only before the peripheral exposing processing or onlyafter the peripheral exposing processing.

A signal from the film thickness sensor 64 is structured so as to betransmitted to the film thickness sensor control unit 68 and undergoprocessing to output a film thickness value, and it is also possible tofind a line width of a pattern formed on the wafer W by changing aprogram of the film thickness sensor control unit 68.

The principle will be explained hereinafter. The signal for the linewidth from the film thickness sensor 64 (such as strength and weaknessof reflected light, for example) is stored in association with the linewidth in advance and saved as the signal data in correspondence with acertain line width value. Having such data beforehand makes it possibleto find the line width on the wafer W by comparing the signal from thefilm thickness sensor 64 with the aforesaid stored data. It should benoted that higher precision is obtained in finding the line width on amensurative wafer by forming a simple test pattern on the mensurativewafer in advance than on a production wafer having an ordinary intricatepattern, on the occasion of practically finding the line width.

Incidentally, it is inevitable that the light source used for the filmthickness sensor 64 is deteriorated with the lapse of time withaccompanying deterioration in strength of the irradiated light. It isdifficult to precisely measure the film thickness when the strength ofthe light from the film thickness sensor 64 is deteriorated. Therefore,a reflecting object 61 a is provided on the mounting table 61 on whichthe wafer W is placed as shown in FIG. 11. It is preferable to embed thereflecting object 61 a in the mounting table 61 so as not to affect theplacement of the wafer W.

In addition, periodically the film thickness sensor 64 is moved to abovethe mounting table 61 to irradiate light for measurement toward thereflecting object 61 a in a state where the wafer W is not placedthereon. As a result, the strength of the light reflected from thereflecting object 61 a can be measured. With deterioration of the lightsource, the strength of the reflected light is also deteriorated,thereby enabling a degree of deterioration in the light source to bedetected by measuring the strength of the reflected light. Thus, it ispossible to detect beforehand deterioration of the light source of thefilm thickness sensor 64, propriety of use thereof, and necessity forreplacement thereof by providing the reflecting object 61 a on amounting table 61.

Moreover, it is preferable to use the test wafer as the wafer W used forthe practical film thickness measurement in the processes of the filmthickness measurement as described above. A plurality of the test wafersare housed in the specialized cassettes C in advance to be distinguishedfrom the production wafers. In addition, the desirable timing of puttingthe test wafer into the coating and developing system 1 is in a break ofa lot of the production wafers, or after coating and developingtreatment is performed on a predetermined number of the productionwafers W.

For example, after coating and developing treatment is performed on theproduction wafer W of one lot, and before the coating and developingtreatment is performed on the production wafer W of the next lot, thetest wafer is put into the coating and developing system 1, coated witha resist in the resist coating unit 15 or 17, subjected to bakingprocessing, and thereafter the film thickness thereof is measured. Whenthe film thickness is within a predetermined allowable range as a resultof the measurement, putting the production wafer W into the coating anddeveloping system 1 is started.

If the film thickness is not within the predetermined allowable range asa consequence of the measurement, necessary corrections such as, forexample, a temperature of the resist solution, a rotational speed, and atemperature of the draft are made to the resist coating unit 15 or 17 inwhich coating treatment is practically performed. After the corrections,resist coating treatment is performed on another test wafer W in theresist coating unit 15 or 17, and thereafter the film thickness thereofis measured.

Then, when the film thickness is within the predetermined allowablerange as a result of the measurement, putting the production wafer Winto the coating and developing system 1 is started. If the filmthickness is not within the predetermined allowable range as a result ofthe measurement, the necessary corrections are again made to the resistcoating unit 15 or 17 in which coating treatment is practicallyperformed, and hereafter the film thickness measurement is carried outwith use of the test wafers W until the film thickness value enterswithin the allowable range.

Thus, resist coating treatment on the production wafer W can always beperformed suitably by inspecting a state in the resist coating unit 15or 17 beforehand.

Incidentally, as a result of the measurement of the film thickness onthe test wafer, when it is within the allowable range, a program of thecoating and developing system 1 is controlled so as to automaticallystart putting the production wafer W thereinto, and when it is out ofthe allowable range, an NG signal, for example, is indicated on adisplay or a control panel of the system or an appropriate alarm isgiven so as to stop putting the production wafer W into processingstation 3, whereby defects of the production wafer W can be preventedfrom occurring and in addition it is possible for an operator toimmediately make the necessary corrections to the resist coating unit 15or 17.

As has been described, the film thickness measurement of the coatingfilm can be performed in the substrate processing system, whereby it isnot necessary to provide a film thickness measuring unit separately,according to the various embodiments of the present invention.Therefore, when the film thickness of the coating film on the substrateis inspected, the time, which is required for transferring the substratefrom the substrate processing system to the film thickness measuringunit, can be reduced. Further, a mechanism in a conventional peripheralaligner can be intactly used, thereby increasing flexibility in pointsfor the film thickness measurement and in addition reducing cost.

It is possible to prevent the impurities, such as the organic substancesgenerated from the coating film on the substrate, from contaminating thesensor portion during exposure. If laser light having a singlewavelength is used, the film thickness can be measured with higherprecision. When a light-emitting diode is used for the light source ofthe sensor member, low power consumption is required, which results in acost reduction. Additionally, it is possible to measure in a large area.Also the line width of the pattern can be measured, and deterioration inability of the film thickness measuring means can be detectedbeforehand. Since the above-described film thickness measurement isperformed before and after peripheral exposing processing, the filmthickness value can be material for determining whether peripheralexposing processing is properly performed or not, whereby the yield onthe production wafer can be improved.

Although the above embodiments describe the wafer processing system inthe lithography in the processes of semiconductor wafer devicefabrication, it is also applicable to processing systems of the othersubstrates besides the semiconductor wafer such as, for example, an LCDsubstrate.

The above-described embodiments have been disclosed with the intentionof clarifying technical meaning of the present invention. Therefore, itis to be understood that the present invention is not intended to belimited to the above embodiments, and various changes may be madethrerein without departing from the spirit of the present invention andwithin the meaning of the claims.

The entire disclosure of Japanese Patent Application No. 11-302214 filedon Oct. 25, 1999 including specification, claims, drawings and summaryis incorporated herein by reference in its entirety.

What is claimed is:
 1. A method of processing a substrate with use of asubstrate processing system, wherein said substrate processing systemcomprises a peripheral aligner for irradiating the peripheral portion ofthe substrate with light to expose a coating film applied on thesubstrate; and wherein said peripheral aligner comprises a filmthickness sensor for measuring a film thickness of the coating filminside said peripheral aligner, the method comprising the step of:irradiating the peripheral portion of the substrate with the lightinside said peripheral aligner to expose the coating film aftermeasuring the film thickness of the coating film on the substrate withthe use of said film thickness sensor inside said peripheral aligner. 2.A method according to claim 1, further comprising the step of measuringthe film thickness of the coating film with said film thickness sensoronce again after exposing the coating film.
 3. A method according toclaim 1, wherein said substrate processing system further comprises acoating unit for coating the substrate with the coating film, the methodcomprising the steps of: using a test substrate as the substrate ofwhich film thickness is measured and performing predetermined coatingtreatment on a production substrate in said coating unit when ameasurement value is within an allowable range as a result of ameasurement of the film thickness with the use of said film thicknesssensor; and measuring the film thickness of another test substratesubjected to coating treatment in said coating unit with use of saidfilm thickness sensor after making a necessary correction to saidcoating unit when the measurement value is out of the allowable range.4. A method according to claim 3, further comprising the step of warningthe outside when the measurement value is out of allowable range.
 5. Amethod according to claim 1, further comprising the step of measuringthe film thickness of the coating film with use of said film thicknesssensor inside said peripheral aligner after exposing the coating film byirradiating the peripheral portion of the substrate with the light bysaid peripheral aligner.
 6. A method according to claim 1, wherein adraft is formed in said peripheral aligner, and said film thicknesssensor is positioned on an upstream side in the draft from anirradiating portion which performs peripheral exposure.
 7. A methodaccording to claim 1, further comprising the step of finding a linewidth of a pattern formed on the substrate by changing a program of acontrol unit of said film thickness sensor.
 8. A method according toclaim 1, further comprising the step of measuring film thickness of aportion which undergoes peripheral exposing processing with said filmthickness sensor and inspecting whether the exposed portion is performedat a predetermined position or not, after completing the peripheralexposure processing.
 9. A method according to claim 1, wherein areflecting object provided on a mounting table on which the substrate isplaced inside said peripheral aligner is included; further comprisingthe step of: irradiating the reflecting object with a light formeasurement from said film thickness sensor in a state in which thesubstrate is not placed on the mounting table, and checking said filmthickness sensor in advance by measuring an irradiated light at thistime.
 10. A method according to claim 1, wherein said film thicknesssensor is moved away from above the substrate during peripheral exposureprocessing.